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EMD DDA40X
The Electro Motive Division DDA40X (nicknamed "Centennial") is a 6,600hp, twin-engine (consisting of two modified 3,300hp 16-645E3A engines), eight-axle diesel locomotive built specially for the Union Pacific railroad from 1969 to 1971. History The DDA40X was mainly built to haul long and heavy trains over the Sherman Hill on UP's Transcontinental route. They were built as part of the railroad's quest for ever more power per locomotive, replacing the much less fuel-efficient GE gas turbine electric locomotives. They were, essentially, an evolution of the earlier DD35 and DD35A, but with more modern feature sets like AC/DC conversion for the traction motors. 47 were built in total, numbering from 6900 to 6946. The "X" in the name stands for "experimental", and many systems were tested in the Centennials, including modular electronics used in the -2 models and later EMD products, an air raid style siren to indicate movement (this was not kept), and integrated load testing for the electronics. The wide cab was the same as the F45 and FP45 cowl units, and lacked the increased structural bracing in modern "safety" cabs. By the late 1970s they began to be withdrawn for storage for economic and repair reasons. An uptick in traffic in the early 1980s had 25 return to usage, but all were retired by 1985 in favor of smaller, cheaper to run locomotives. 13 are preserved and the rest were scrapped. Only one (UP #6936) is currently in service as a heritage unit. Trivia *The DDA40X is often referred to as the "Centennial" to celebrate the 100th anniversary of the completion of the Transcontinental Railroad. *The DDA40X was one of the first types of EMD locomotives to have a "wide nose" before the official "safety-cab" era began in the 1980s. *Several DDA40X locomotives are preserved, but 6936 is the only to still remain in service only to pull special passenger excursions. *"DD" indicates the unit has 2 trucks, each with 4 powered axles, yet the EMD "DD" units are sometimes referred to by railfans as "Double Diesel". *Large sandboxes were added to the sides of the DD35 and DDA40X above the rear trucks due to a flaw in the DD35's rear sand box which developed cracks that fouled the electrical cabinets with microscopic sand particles. *The 4 axle trucks also required more sand than tradtional 3 axle trucks. Hence, the need for having large sandboxes mounted on the sides of the units. *The first of the engines; 6900, currently resides in Kenefick Park, Omaha, Nebraska, the current location of 4023 Big Boy as well as Union Pacific's corporate headquarters. *The UP's renumbered fleet of GE AC6000CW units retain the same numbers that their giant DDA40X predecessors originally retained. Media * PicSearch * VidSearch UP DDA40X siren.jpg|The siren horn used on DDA40X #6918 (with the original airhorn in the background). UP DDA40X siren 2.jpg|The siren-equipped DDA40X (as seen in a magazine article). UP DD35.jpg|A DD35A UP 6900.jpg|UP #6900 awaiting to couple and arrange the "Golden Spike" ceromony train to haul to Odgen, Utah for celebration. UP 6941.jpg|UP 6941 pauses for a crew change in Cheyenne, Wyoming in 1979. The train was the super hot Falcon. This was a combined C&NW / UP TOFC train. DDa40x.jpg|UP #6938 is leaving a yard with a freight train. Wy233.jpg|UP #6900 with UP #8444 and Virginia and Truckee No. 18 "Dayton" dressed up as the Union Pacific's No. 119. Category:EMD locomotives Category:Diesel Locomotives Category:Eight-axle Diesel Locomotives Category:American Locomotives Category:DC Traction Locomotives Category:Union Pacific locomotives